1. Field of the Invention
This invention relates to a novel method for producing an electrically insulated conductive body by utilization of electrophoresis. The method according to the present invention is particularly suited for production of electrically insulated conductive bodies such as coils, etc. used in electrical apparatuses and appliances.
2. Description of the Prior Arts
Production of the electrically insulated conductive bodies such as a coil, etc. for use in electrical apparatuses and appliances has heretofore been done by impregnating the coil made of electric conductor, which is wound together with inorganic-organic composite type porous insulating material, with an impregnating resin containing therein curing agent, curing catalyst, curing accelerator, and so on, followed by heat-setting the impregnated resin.
Such conventional method, however, has various disadvantages such that a great deal of man power is required for winding the porous insulating material together with the electric conductor, which inevitably lower the working efficiency; the socalled "dropping phenomenon" takes place due to lowered viscosity in the resin composition when the impregnated resin is to be cured under heat; in view of the fact that the impregnating resin contains the curing agent, a curing catalyst, and a curing accelerator as its composition, the resin tends to be cured when left over a long period of time, hence its usable period of time is inevitably restricted; and, for the preceding reason, maintenance and control of the storage vessel for the impregnating resin is rather complicated.
The present inventors have so far developed various methods for forming an electro-deposited insulating layer by electrophoresis using electrodeposition paint consisting of mica and water-dispersion varnish (vide: Laid-Open Japanese Patent Application No. 89178/76 and No. 114602/76), the methods being capable of dispersing with winding the electrical conductor together with the porous insulating material, which has been one of the disadvantages in the abovementioned conventional method for its production.
These forming methods, however, have such a disadvantage that the mechanical strength of the electrolytically deposited insulating layer at a stage prior to its impregnation with the impregnating resin is weak, which weakness causes cracks and tear-offs to occur in it when the insulating layer is fitted inside a slot of an iron core.
As the result of diligent and strenuous researches conducted in an attempt to remove the defects in such forming methods as well as those remaining in the conventional methods, the present inventors have discovered that all of the abovementioned defects could be solved by immersing the electrolytically deposited insulating layer, after its formation, into an aqueous solution added in advance with the curing accelerator, based on which discovery they completed the present invention.